Most electrical appliances, such as TV sets and air conditioners, will have the standby power consumption of about 10 w after being shut down with the controller, so will desktop computers. To thoroughly eliminate such standby power consumption, it is required to completely shut down the power supply of the electrical appliance; however, after the power supply is completely shut down, it is required to turn on the power supply before restarting the electrical appliance, which does not comply with the habit of most people.
Therefore, people have invented power-saving switches or power-saving sockets, most commercially available power-saving switches or power-saving sockets adopt mutual-induction transformers, which first compare the start-up current of the electrical appliance with the standby current of the same, and then completely shut the power supply through a relay control circuit for connecting or disconnecting the power supply of the electrical appliance, thus achieving the purpose of eliminating standby power consumption; however, such a power-saving switch or power-saving socket will need complicated procedure to connect the power supply of the electrical appliance:
For example, the power-saving socket for TV sets generally adopts a 2 m multiple-core cord which connects an infrared receiver with the power-saving socket, in practice, it is required to fix the infrared receiver before the TV set first, when the user press the power button on the controller for the first time, infrared receiver will only make the relay control circuit of the power-saving socket to connect the power supply, and the TV set will be really started after the user press the controller for the second time power button on the;
The power-saving socket for computers generally adopts a 2 m multiple-core cord which connects a touch button with the power-saving socket, in practice, it is required to fix the touch button before or near the computer, to start the computer, the user needs to press the touch button once to make the relay control circuit of the power-saving socket to connect the power supply to set the computer at the standby status, and the computer will be really started after the user press the power button of the computer;
Other electrical appliances will also need complicated procedure to make the relay control circuit connect the power supply, although the power-saving sockets mentioned above do same power-saving, they use multiple-core cords which are both expensive and too thick to be fixed, moreover, they looks not graceful, and more important, when such sockets are used, although the shutdown of the electrical appliances can be in one step, the startup can only be done in two steps, which does not comply with the habit of most people.